1. Field
This invention relates to configuration of multiservice access devices, more particularly to methods of configuring them to handle oversubscription and a multiservice access device capable of being oversubscribed.
2. Background
Multiservice access devices allow networks to handle all types of traffic such as voice, data and video. These devices are normally configured with a set number of permanent virtual circuits (PVCs) and switched virtual circuits (SVCs). Examples of this device include multiservice access switches and multiservice access concentrators.
PVCs are point-to-point configurations between devices connected by a network. They are configured before any traffic is sent, and once configured they remain in place. SVCs only exist as long as the two devices communicate, and are established at the time the transmission is required. As soon as transmission between the devices stops, the circuit is disbanded.
The disadvantage of PVCs lies in the configuration parameters of the connections. Since the circuits are established ahead of time, they typically are configured with a type of service. The type of service specifies the nature of the transmission rate for the PVC. The services include constant bit rate, variable bit rate-real time, variable bit rate-non-real time, and unspecified bit rate. The first three have guaranteed throughputs, and constant bit rate service has a constant throughput as well. PVCs connected with unspecified bit rates do not have guaranteed throughputs.
Multiservice access devices that utilize PVCs for handling traffic typically handle oversubscription on the device by converting oversubscribed PVCs to unspecified bit rate service. Therefore, a method and apparatus is needed that will allow oversubscription in a more efficient manner and increase the usefulness of the device.